This invention relates to improvements in steering column assemblies.
It is known to provide a steering column assembly. The assembly can be adjusted for reach allowing the steering wheel to be moved towards and away from a driver, or for rake allowing the steering wheel to be moved upwards and downwards relative to the driver. This allows for a comfortable driving position to be achieved and, where provided, for the optimum positioning of a driver airbag attached to the steering wheel relative to the torso of the driver. A steering column that adjusts for reach or rake is known as a single adjust assembly, and one that adjusts for both is known as a double adjust assembly.
It is important that the assembly is easy to adjust when required and yet fixed rigidly in position when the vehicle is being driven. This is achieved by providing a steering column shroud which surrounds a steering column shaft that supports the steering wheel. The shroud is fixed in position by a releasable clamp assembly. When the clamp assembly is in a clamped condition the shroud, and the wheel, are fixed relative to a part of the vehicle, typically the bulkhead. When it is in an unclamped position the shroud is free to move relative to the bulkhead so that the position of the wheel can be adjusted.
Several clamp assemblies are known, but a most common type includes a clamp mechanism which can be released or locked by rotation of a handle attached to a clamp pin or bolt. The handle is fixed to a first part of a cam mechanism which rotates with the handle about the axis of the clamp pin or bolt. A second part of the cam mechanism is prevented from rotating and co-operates with the first part. Rotating the handle moves the two cam parts relative to each other, which increases or decrease the overall length of the cam mechanism depending on which way the handle is rotated. This change in length of the cam mechanism provides the locking function of the clamp assembly.